Apparatus and method for electrical transmission of pictures



March 29, 1932. e. s. VERNAM ET AL APPARATUS AND METHOD FOR ELECTRICALTRANSMISSION OF PICTURES Filed Dec. 15, 1925 2 Sheets-Sheet l g N [N VENTORS g 61.5: vmm zffin mma B y 21?. P611 7 A TTORNEY 19215 2Sheets-Sheet 2 Mar h 29, 9 2- e. s. VERNAM ET AL APPARATUS AND METHODFOR ELECTRICAL TRANSMISSION OF PICTURES Filed Dec. 15

IN VEN TOR MUM;

A TTORNEY of area'and transmitting code combinations,

" lying portion of the film 12 falls on the pho- Patented Mar. 29; 1932GILBERT s. vER1vAM, or RIvnREnGE, EwfJnRs-Ei. ANIIYEDWAYRD nl wa'rsoiv,or

. V 'ranorriuoiv r, AND DONALD B. PERRY,

F .YoNKERs, new YORK, 3ASSIGNORS-TO AMERIGA'N TELEPHONE ANDTELEGRAPHflOMPANKJA CORPORATION OF,- -Y ORK Q APPARATUS AND METHOD non Ewmm mwsmssma onrrcrngans Q Application filed December 15 1923. erial No.1,007.. I

' The principal object of our invention isto providea new and improvedmethod and suitable apparatus for transmitting pictures "ma distance byelectrical impulses. An-

nuniberof elements in thesequence. These 1 other object 'of'ourinvention is to provide corresponding to the degree of shade of thesuccessive elements. Anotherobject of our invention has relationj totransmitting asingle, code combination for a sequence of elementsof likeshade, the combination indicating both" the degree of that shade and theand various other objectsand advantages of our invention will becomeapparent on consideration of the specific example of the practice of theinvention which wehave chosen to disclose in the following specificationand illustrate in the accompanying drawings. It will be u'nde'rstoodthat the inventionis, de-

fined'in the appended c-laimsand that the following specificationrelates to the particularexample'here presentedto illustrate theinvention. I I I Referring to the drawings, Figure -1' is a diagramshowing the, transmitting apparatus, Fig.2 is a plan showing the code aspunched in a section of tape and Fig; 3 is a diagram showing thereceivingv apparatus. The picture to be transmitted is in the form of asemi-transparent film 12 which is wrapped aboutthe glass drum, 10;thisis rotated on its axis ,and'meanwhile traversed relatively slowlyalong its axis so that the portion 'of the film 12 adjacent to theopening in the screen 13 describes a helical course of adjacent turnson'the film 12. The light from, the source 14 shining through. the'openingin the screen 13 and through the undertoelectric cell 15. The current inthe circuit of the cell 15 is accordingly varied in corjr'es'pondencewith the varying degree of shade in the'spot of the film 12 adjacent tothe opening in the screen 13. This varying current relays A; B and C arein the output circuit of the amplifier 16. The adjustments'are I suchthatgfor a part ofthe-liln'1f12corre-v spending to" White none ofthe're'lays or -(J will pick-up;v for light grey only 'will :pickup, asshown in Fig. 1; for dark'grefy 'A and B will pickup but notG andforblack all three relays A, B and(} will pick up. The cams '18 and 19:rotate once for each,

unit or element of the picture film 12 lying under the opening of thescree'nll3.

is punchedwith a code cornbinationjwhen the shade changesjto indicatethe preceding shade and to ind1cate the'-*'nu1nber of picture e1e ments'in sequence having that same'sh'ade.

The'co'de employed is the usual'fi've unit code I shade. As shown inFig. 2, this number of units permits countinga number of-elements up" toseven inclusive,-and as will be pointed out presently, if a sequence ofseven elements of like shade is encountered in the picture .to betransmitted, the countis made to seven and then the apparatus is clearedready to repeat. Suppose that a'singl'e'whit'e' unit inthe 'pic'-.

ture film 12 is to be transmitted." Aglance elements in the sequence"havlng' the same atFig. 2 shows that-the corresponding code Iimpression in the-tape comprises-i holes punched in the first andthirdfpo'sitions; the punch in the first position meaning a single unitand the punchin the third position meaning the white shade. As alreadystatdyfor the white shade the current in the output circuit ofthe-amplifier 16 will be so low that none'of the marginal re lays A, Band C will be operate'd'an'd their armatures will all be ontheir back'contaots at the left. f 5 With thearmatureof relay A onits back contact,relay a will been'er ized so 'that'whe'n cam 19 closes contact'25 acircuit-will bemade "through the back'contact of relay "0;: upper frontcontact of relay a' 'back contact of relay a to the perforatorrelay 20,whichwill cause the latter to lock up and energizethe punch magnet 21-.'This will punch the tape f28 v The tape 28 '(shown'both in F igs. ,1and upper winding of relay a and causesit to operate. 'Also, theoperation of-thepunch magnet 21 breaks the locking circuits for relavsb" and and releases them if they or either of them had previously beenlocked up also the operation of the punch magnet21 releases any of thecounting relays 1a, 1b, 2a, etc., that may have been locked uppreviously.

The operation of the punch magnet 21 also breaks the locking circuit forthe perforator relay 20, which opens and thereby releases the punchmagnet. The release of the punch magnet then closes a circuit frombattery 23.

through the lower back contact of relay 0 and the lower winding andfront contact of relay a to energize selector magnet 3 and also lock uprelay (1.

Y The cam 19 continues to rotate and closes the contact at 24, thecounting contact. This closes a circuit from battery,rthrough the upperback contact of relay 0, the back contact of relay 1b and the winding ofrelay in, which operates accordingly. This connects battery 23 throughthe armature of 1b and the armature of 1a to the winding of 16, butlb-does not operate at this time because it is already shunted by thelow resistance path just traced through the contacts at 24-, 0 and 1b. 7

Also, the operation of relay 1a closes the circuit for selecting magnet1 and causes it to per When the counting contact 24 opens, this opensthe shuntaround relay 1]), which operates and transfers the countingcircuit -(throughthe upper back contact of relay 0) so that now, insteadof connecting to 1a and 16 it connectsto 2a and 2b.

We have already assumed that only a sin gle element of white shade is tobe transmit tedso that accordingly the shade will now change, Assumethat it changes to light grey. Marginal relay A willbe energized andrelay a will be released. When the cam 119;.makes the contact 25, acircuit is closed from ground, through the contact 25, back contact ofrelay 0, back contact ofa, front contact-of'a to the perforator relay20. This operates as described before and the punch magnet. 21 operatesas described before, and selector magnets 1 and 3 having been previouslyenergized, holes are punched at the first and third positions, as shownin Fig. 2. The operation of the punch magnet 21 releases thecountingrelays by breaking their circuit at the contact adjacent tobattery 23 and the system is ready to start overagain. I e

Let us go back and suppose that instead rater relay will not operatebecause its of a single white element in the film 12 there were fivesuch elements in succession. Then, when the punch contact 25 closes,instead of getting the, result last described,,.the perfocircuit will beopen at the back contact of relay us. However, the counting contact-24will close a circuit from battery, through the upper back contact ofrelay 0'," front contact of relay 16, back contact of relay 2b, throughthe winding of counting relay 2a, which will opera-tent once. By theoperation of 2a, battery 23 will be applied through the windofr'elay'2b, and as soon as the contact 24 opens, opening the shunt around26, battery '23 will become effective and operate 2?) as well as 2a..

On the next revolution of the cams 18 and 19 corresponding to the nextelement of the picture film 12, counting relays 3a and 3685 will beoperated and locked up in similar manner. Thenon the next rotation ofthe camslS and 19 for another element of film 12, relays la and 46 willbe operated in like manner. It will be noticedthat relay 4a has itswinding in series with a winding of relay -10 so'that relay 10 operatessimultaneously with 40 and 4c locks up by currentifrom the battery Also10 closes a direct circuit from battery through the selecting magnet 4:.i 7

When 7 the counting contact at 24 opens after the fourth count, relay 46operates by reason of the opening of the shunt around it. The operationof 1b breaks the circuit from T00 battery 23 to the relays 1a, 1b, 2a,2b, 3a and 3b and allows them torelease. Then, when 2hrcleases it breaksatits rightehand front contact the circuit for 4a and 4b and theyrelease, but 4-0 remains locked up.

' On the fifth revolution of the-cams 18 and 19 corresponding to thefifth successive element of white shade in the film 12, relays 1a and1?) are operated again successively upon the closureandsubsequentopening of the contact 24, causing selecting magnet 1 to beoperated. After the fifth revolution the shade changes in the film 12,operatingone or more of the relays-A, B and C and thus, as describedheretofore, establishing a circuit for the perforator relay 20 andallowing the punch magnet 21 to operate and punch holes at positions 1,3' and l, indicating a sequence of five white elements shown in Fig. 2.The operation of the punch magnet 21 clears 12 0 the counting relays bybreaking the circuit from battery 23, as previously described.Tfa'sha'de recurs more than seven times in succession a punch will bemade on the seventh count andthe count will be begun I again for anotherseries. -WVe have already seen that on the fourth count the relay 410locks up; on the fifth count 1a and 1b are operated; on the sixth countrelays 2axand 2b are op- 3 erated and'on the seventh count relays 3a andon the right a circuit from battery, through theiupper winding ofperforator relay 20, in'- ner leftcontact of relay 40, back contact ofrelay 4a, rightfront contact of relay 3b, and this circuit iscompletedat 25 to operate the pertorator relay'20 and the punch magnet21. The Operation of the punch magnet 21 in the tape. QThese fivecontacts controlcirpunches holes in the second andv fourth positions toindicate seven'elements of likeshade andother holes (or a blank) inother positions to indicate the degree of shade also the 'operation'ofthe punch 1nagnet2l clears out the counting relays, as describedheretofore,- ready to begin over again. 7 A contact 26 at thetransmitting drum 10 is closed through battery 27 at the edge of thefilm '12. The circuitthus" established through the winding of relay c-jenergizes the latter and closes the upper front contact of relayc so thatwhen the punching contact is made at 25 the circuit is closed for theperforator relay 20, thereby causing the punch magnet 21 to punchwhatever combination happens to be set up at that time, that is when theedge of the film 12 is reached by the contact 26. The operation of thepunch magnet 21 clears out the counting relays. 'as has been describedand causes theirelay c to be picked up and locked up by current from thebattery 23.. This condition .continues until the'other edge of the film12 reaches the'contact 26 and breaks it;"duringthis time both thecircuitfor'periorator relay 20 and the counting circuits are held open at'theupper backcontacts of relays 0 and c. 7

But at the other edge of the picture when the contact 26 is broken,relay 0 releases and the circuit for perforator-relay 20 is establishedthrough the upper back contact of relay a and a frontcontact of relay 0,which remains, locked up. "The circuits ofselector magnets 3 and 5 areboth openat the lower back contact of'relay 0 at this time, and when thecontact 25 is closed and theperforatorre lay'20 operates, causing thepunch magnet 21 to operate, the blank combination will occur on thetape, which is the code for carriage return and line feed. T'ThlS willbe explained -further in connection with the discussion of the receivingapparatus that is'to follow.

The cam 18 closes briefly for'each element of the picture, shunting outthe marginal re-' lays A, B and C; this allows them to operate always onthe same point on their magnetiza- I time to elapseafter the contact Topens for ficient time, to release and operate again before the nextpunching-operation.

The tape produced at the sending end'according to the code of Fig. 2 isput through a tran-smitterand thereby at the receiving end This receivedtape is-passed through the tape transmitter 34, 34 of'F1g.

3, which is of a type used iii-printing telegraphy; The drawing is meantto indicate symbolically that the contacts numbered from .1 to 5adjacent to 34 are closed to thebattery 35,for'each hole in theco-rrespondingposition cuits to the respective relays 11,22, 33,44and55," of which 11, 22 and 44; are count selecting lays.

relays and 33 and 55 are shade selecting re-s Theperforatedt'ape 28at'the receiving end passes from theperi'orator 51 to the tapetransmitter 34: me loop under the member 52 so arranged that when thetape 28' is pulled up it will cause the circuit of magnet 53 to openandstop the operation of the receiving printer; I

The'printingis done on a page in a page printing receiver inwhich theprinter select-- mg magnets 110, 220,330, 440 and 550 areemployedJ Themagnet 110 is unnecessary for picture printing, and the remaining fourmagnets mentioned operate according to the -following code:

Prin ter selecting magnets operated Characters printed a other Printerperations t .330 Space or blank V y l None Small dot Y i 5501 a Mediumdot 330,440,550 Large dot 44:0 Carriage return f 220 Line feed Thisparticular code arrangement is shown as one suited for use in connectionwith certain ordinary printing telegraph machines" now widely used.

34, in" readiness so that one step will bringit' through the windings ofthe clear-out relay 31 and the tape transmitter magnet 32 to-battery.-Upon the closure of this circuit the clear-out relay 31' and the tapetransmitter magnet 32 are operated, and they release when the circuitopens at T; v

The cam 38 is designedto allow a suflicient the tape transmitter magnet32: to release and for the transmitter contacts'at 34toe'n'ergize therespective relays with which they are connected beforethe contact Scloses at 38.

7 If relay 33 of the two shade selectingree lays is energized, then whencontact S closes r 1 The tape-is'ins'erted in the tape transmitter tothefirst code combination of the picture.

fi io battery .36 will be connected through printer h selecting magnet330. This will'cause-the printerato record a space or blank 'as indi- 2to a new signal combination. The actuation cated in the foregoing table.

; been set up in the tape transmitter.

If relay 55, but not 33, is energized, the contact closure at S willconnect the battery to printer selecting magnet 550 anda medium dot-willbe printed. If relays 33 and 55 are both energized, then contact'closureat S will apply battery to magnets 330, 440 and 550 in parallel and alarge neither relay 33 pulse will be sent dot will be printed, If

through the printer selecting magnets, and a small dot will be printed.

For an example to explain the action of the counting relays 11, 22 and44, let it be assumed that the code combination 1, 2, 5 has A referenceto Fig. 2 shows that this corresponds to a sequence of two medium dots.The transmitter contactsat 34, numbered 1, 2 and 5, will be closed tothe battery 35, and there fore the relays 11,22 and 55 will beenergized. When the cam 38 closes contact S, printer selecting magnet550 will be energized thus preparing the printer for recording a mediumdot. At the same time the relay 11a will be'energized by the closure ofthe contact S through a circuit from battery .36 through the backcontact of relay 115. Accordingly the relay 11a will connect battery 39to the lower end of the winding of relay 11?), but relay 11?) will notoperate until contact S opens, because meanwhile relay 11b is shuntedthrough said contact S. When relay 115 does operate, it transfers thecounting circuit 37 to the armature of relay 22b and thence to thewinding of relay 22a.

As the cam 38 continues to rotate, contact T will be closed and willconnect ground through the front contacts of relays 11 and 11a to thearmatures of relays 22, 220; and 33a, but as these are all opened, thetransmit ter magnet will not'be energized. When contact S closes on thenext revolution, the printer selecting magnet 550 will be energizedagain to cause the printer to record another medium dot, and relays 22aand 225 will be energized in succession in the manner heretoforedescribed for 11a and 116. Then when contact T is again closed by thefurther rotation of the cam 38, ground will be connected through T andthe, front con tacts of relays 11, 11a and 22a and the back contact ofrelay 44 to the windings of the clear-out relay 31 and the tapetransmitter magnet 32. The tape will now step ahead of the clear-outrelay 31 establishes a direct circuit from ground through the contact Tandfront contact of relay 31, through said relay 31 andthe tapetransmitter magnet .32;

i this insures that the tape transmitter 34 will receive a full lengthimpulse. The opening of the back contact of relay 31 removes battery 39from the counting relays and releases them. In what goesv before, wehave traced the nor 55 is energized, no imoperation for the codecombination 1, 2 and 5 corresponding to a sequence of two medium dots asshown in Fig. 2.v 1 and 2 determine the count and 5 determines theshade. As-

suming that the shade is the same, other set- 770 tings of the countselecting relays 11, 22 and 44 will cause the selected shade characterto be recorded a different number of times as follows:

If relay 11 is energized alone, the tape feed circuit controlled at Twill be closed through the front contacts of relays 11 and 11a and backcontactsof relays 22 and 44 after a single contact closure at S. Ifrelays 11 and 22 are both operated, the said tape feed circuitcontrolled at T will remain open until contact 5 has operated twice asin the case previously followed through in detail. If relay 22 alone isoperated, contact S must operate three times so as to energize relays11a22a and 33a and then close the tape feed circuit controlled at Tthrough the back contact of relay 11, front contacts of relays 33a and22a and back contact of relay 44.

If relay 44 alone is operated, four revolutions of the cam 38 must takeplace which will operate all four of the pairs of counting relays.Therenpon, with the operation of the relay 44a, the repeat relay 41 willoperate and lock by current from battery 39. Relay 44b releases all thecounting relays to the left thereof, and relay 33b then'releases 44aand44?) so that after four operations of contact S the repeat relay 41 isthe only relay remaining energized of the counting group. The ape feedcircuit controlled by T is now closed through back contacts of relays11, 11a and 22 and the upper front contact of repeat relay 41. If relays11 and 44 are both energized, the tape feed circuit controlled by T willbe held open until the repeat relay-41 pulls up on the fourth revolutionas described above and until'relay 11a is energized again by the fifthoperation of contact S. The tape feed circuits from T for this case offive characters, and also for the cases of six or seven characters, arethe same, respectively, as for counts of 1, 2or 3 as describedheretofore, except that in each case the tape feed circuit extendsthrough the front contact of the relay 41 instead ofthe back contact ofrelay 44.

The foregoing description covers the operations of printing from oneto'seven like characters from the respective code combinations of thetape. The carriage return and line feed operations which are determinedwhen no holes are punched in the tapewill now be described. In this casewhen the contact T opens, the tape transmitter contacts at 34 will allbe held away from connection with battery 35, and all five selectingrelays 11, 22, 33, 44 and 55- will remain deenergized. Then when contactS closes, a'circuit will be established from battery-36, through backcontacts of relays44, 22, '11 and 22b to printer select ing magnet 440,which, in accordance withthe foregoing table controls the carriagereturn operation of the printer. Relays 11a and 11b 7 22a and 226 willbeenergized. Then whencontact S closes the third time, an impulse willbe sent through printer selecting magnet 220, instead of 440 (due to theenergization of relay 225). This causes the printer to feed the paperone line in accordance with the last entry in the foregoing table, andat the same time relays 33a and 38?). areenergized. When contact Tcloses, the tape transmitter magnet 32 will be energized over a circuitfrom T, through back contact ofrelay 11, front con.- tacts of 33a and22a, back contact of relay 44, winding of relay 31 and tapetransmitter 1magnet 32 to battery.

Thus it will be seen that, with the tape' reproduced at thereceivingstation in accordance with the code of Fig. 2, the codecombinations control the receiving printer to printa space or a dot ofvarying size and to repeat each such space or dot any number of timesfrom one up to seven, and automatically to perform the operations ofcarriage return and line feed. T

We claim: 7 1. In a picture transmitting system, means to exploresuccessive elements of the picture a V v I CODdItIlOll of said tape.forcontrollmg the.

and to automatically transmit code currents corresponding both to thenumber of elements in a sequence. of like shade and to the shade of theelements of, such sequence, means for varying sald code currents inaccordance with the numberof elements in a sequence,

. and means to receive such currents and reproduce thepictureaccordingly.

2. In a picture transmitting system,'means to automatically exploresuccessive elements of the picture and to punch code combinations in atape corresponding both to the number of elements in a sequence of likeshade and the shade of said sequence, said code combinations varying inaccordance with thenumber of elements in a sequence and means toreproduce a similar tape at the receiving end and therefrom pictureaccordingly.

8. In a picture transmitting system,means to automatically produce atape punched with code combinations to represent the number of pictureelements in a sequence of eleto reproduce the ments of like shade and torepresent that shade, said code combinations varying in accorda'nce withthe number of elements in a sequence, means to impress a character ofcorrespondlng shade at a correspondlng posltion on a picture receivingsurface, and means pulses in a'sequence off like strengthtosaid relays,means operable on change of strength to repeat .tha tsame-character'insuccessive;

in.v successive impulses 'to v recordjthe number of impulses inthecountedsequence and the degreeof strength of those impulses and pic-.,

ture reproducing means responsive to the" cor pul e V.

5; In picture transl nission system,"marginal relays,'a circuittherefor, means to auto;

matically send sequences of current-impulses to'said relays,gcountingrelays, meanstoop-f V 852 I erate the countingrelays fora sequence ofimpulses of equal-strength through themar-g ginal' relays, means-torecord the count af d also tojrecord the number and N degreej ofstrength vo f the impulses whenthe degreeof strength of those impulseschanges through the marginal relays and picture ,re'; ducingmeansgresponsive to -,the recorded,

' impulses. i V

6. In a picture transmission system,

combination of atape perforator, meansforv operating said perforator maccordance with receivedfcurrent corresponding characteristics, a' tapetransmitterto jbe op' erated bythe tape from said perforaton'pi c: turereceiving apparatus controlled by saidtransmitter, and means dependingupon the speed of said, receiving 7 apparatus.

' 7., In a picture transmiss onsystem, a "105,

perforator, means for operating said perforator n. accordance withreceived currents r sia e' ns Pic re iqhar t s esaa,

said tape, picture receiving apparatus controlled byrsaid transmitter, astopv forsaid apparatus, magnet and a a, control circuit for said stop,and aswitch for said circuit governed by said tape. 7 e I 8. In aplcture transmitting system, means to explore success ve elements of theplcture,

tape transmitter governed in its operation means to count the number oflike elements in a sequence, means to make a record of said count, saidrecord varying in accordance both with the numberof elements in asequence and with their shade, means to transmit code currentscorresponding to said record, and means to receive such currents andreproduce the picture accordingly.

9. In a picture transmitting system, means to automatically produce acode record with code combinations in accordance with both the number ofpicture elements in a sequence of elements of like shade and inaccordance with that shade, means to impress a corresponding degree ofshade at a ing surface, and means to repeat that same impression insuccessive positions on that surface the number of times correspondingto the number embodied in the code.

' 10. The method of transmitting a picture Which consists in analyzingit into sequences of elements of "like shade, automatically transmittinga-code combination of currents for each sequence, each combinationvaryingin accordance With the number of elementsin the sequence andtheshade of those elements, and reproducing the-picture from thesecurrents.

11. The method of transmitting a picture which consists in analyzingitinto sequences of elements of the same shade, for each sequence of adifie'rent number of elements automatically transmitting a correspondingcode combination, and for each such code combmation received printing asequence of characters of the'corresponding number and shade on areceiving surface.

12; In combination, a picture having groupsot elemental areas the sizeof each group determined by the number of successivearea's with the samedegree of shade, means for testing and counting the number of elementsin a group, and meansresponsive to said count for making asingle coderecord indicating the number of elemental areas counted and their degreeof shade.

13. The method of transmitting a picture, Which consists in exploringits elements successively for degree of shade, counting the elements oflike shade in sequence, recording a code combination for the number ofthe sequence and the shade when the shade changes, and reproducing thepicture from this record.

In testimony whereof We have signed our names to this specification this13th day of December, 1923;

. V GILBERT S. VERNAML EDWARD F. WATSON.

DONALD B. PERRY corresponding position on a picture receiv-

